Automatic leveling mechanisms



Dec. 8, 1959 Filed Aug. 30, 1956 E. J. PARKINSON 2,915,961

AUTOMATIC LEVELING MECHANISMS 5 Sheets-Sheet l INVENTOR. EDWARD J. PARKINSON AT TORNEYS Dec. 8, 1959 E. J. PARKINSON 2,915,961

AUTOMATIC LEVELING MECHANISMS Filed Aug. 30, 1956 5 Sheets-Sheet 2 F l G. 3 INVENT EDWARD J. PARKIN N sy ATTORNEYS Dec. 8, 1959 E. J. PARKNSON 2,915,961

AUTOMATIC LEVELING MECHANISMS Filed Aug. 30, 1956 3 Sheets-Sheet 3 INVENTOR.

EDWARD J. PARKINSON FIG. 4

ATTORNEYS nitecl States 2,915,961 Patented Dec. 8, 1959 AUTOMATIC LEVELING MECHANISMS Edward John Parkinson, Saginaw, Mich., assignor to Goulding Manufacturing Company, Saginaw, Mich.

Application August 30, 1956, Serial No. 607,226

13 Claims. (Cl. 10046)' This invention relates to certain novel and highly useful improvements in automatic leveling mechanisms.

In many industries it is necessary to employ a plurality of pressure fluid cylinders to move one element or unit relatively to another because the element may be of such length and weight that a single cylinder will not suflice. In the design of presses for the plastics industry, for example, it is often desirable to employ a platen of considerable length and, unless the platen is to be of unduly heavy design, it must be moved by more than a single pressure fluid cylinder or there will be considerable deflection of the ends of the platen. Consequently the use of plural cylinders has become common, however, considerable difliculty has been encountered when spaced apart cylinders are used, even though both cylinders are supplied by the same source, because one ram will tend to lag or lead the other dependent on the load applied to a particular end of the platen. A lack of uniformity in the resistances opposing travel of the respective ends of the platen will cause one ram to move faster than the other. This causes canting of the platen and obviously prevents proper and efficient operation of the press because the die elements then bind and are subjected to severe stresses. Various mechanisms, which have thus far been of relatively complex and expensive design, have been suggested to maintain the cylinders in such a system in synchronism; however, none have to my knowledge proved commercially successful nor adaptable to presses of the type which will be described.

One of the prime objects of the present invention is to provide an improved automatic leveling mechanism responsive to uneven movement of the rams in the cylinders for maintaining a plurality of cylinders in substantial synchronism regardless of the load distribution on the cylinders. The leveling mechanism of the instant invention employs a unique mechanical system for measuring unevenness of the rams which can be efficiently used with presses having platens of considerable length and in areas where head room is limited.

Another object of the invention is to design leveling mechanism of the character described for automatically varying the supply of pressure fluid to a particular cylinder and holding the lag or lead within a certain predetermined differential measurable in thousandths of an inch when an uneven load distribution tends to create lead and lag conditions.

One of the principal reasons it is believed the instant leveling mechanism has proved successful is because the flow of fluid to the cylinders is metered in accordance with uneven travel of the rams in a manner to precisely control the quantity of fluid which is supplied to each cylinder and the rate at which it is supplied. It will be seen that the instant mechanism is designed so that the rate of flow to a given cylinder may be increased or decreased only the amount necessary to permit one ram to'overtake the other. While the one ram is overtaking the other to level the platen, the amount of fluid being supplied to each ram is being regulated in accordance with the unevenness of the rams during the interval of correction so that the mechanism does not hunt.

Broadly, the invention relates to a fluid pressure system for driving the platen moving rams, a mechanical system responsive to a non-uniform travel of the rams, regulating means operative to control the amount of fluid supplied to drive the rams at a particular instant, and means actuated by the mechanical system directly operating the regulating means in a novel manner in accordance with the scope of the unevenness at that instant.

Specific objects of the invention reside in the precise control of the fluid supplied to each cylinder by mechanism of simple and economical design, and the efficiency and reliability of the mechanism.

With the above and other objects in View, the present invention consists in the combination and arrangement of parts' hereinafter more fully described, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims, it being understood that equivalent changes may be made in the various elements which comprise the invention without departing from the spirit thereof or the scope of the appended claims.

In the drawings:

Figure l is a side elevational view of one type of press on which the mechanism may be employed showing particularly the mechanical system for measuring the lag or lead of one of the cylinders with respect to the other and actuating the fluid control means accordingly, the traveling platen of the press being shown in down position.

Figure 2 is a partly sectional elevational View of the fluid metering assembly only.

Figure 3 is a transverse sectional view thereof taken on the line 33 of Figure 2.

Figure 4 is an enlarged fragmentary view illustrating in some detail the manner in which the lag or lead measuring system is operatively connected to the fluid metering assembly.

Figure 5 is a fragmentary side elevational view taken on the line 55 of Figure 4.

Figure 6 is a transverse sectional View taken on the line 6-6 of Figure 4.

Figure 7 is a sectional plan view taken on the line 7-7 of Figure 6.

Figure 8 is a schematic view illustrating a pressure fluid circuit for supplying pressure fluid to the rams.

Figure 9 is an inverse sectional plan View taken on line 9-9 of Figure 4.

Referring now more particularly to the accompanying drawings in which I have shown a preferred embodiment of the invention a letter P generally designates a hydraulic press of the downward pressure type which is shown as including base legs 10 supporting a stationary platen or die bed 11 on which a suitable die 12 may be mounted for cooperation with a press head or movable platen 13 and the die 12a carried thereby. The vertically movable platen 13 is supported on a pair of cen trally disposed slide rods 14 which extend through suitable slide bearings 15 in the press bed 11 and it Will be noted that the upper ends of the rods 14 can be reduced as at 14a to provide annular shoulders for supporting the ends of the platen 13, and that the upper ends of the rods are threaded as at 14b so that nuts 16 may rigidly clamp the platen 13 on the rods 14. The lower ends of the rods 14 can be similarly reduced as at 14c to receive couplings or links 17 and 1701 which connect the rods to the rams or pistons 18 and 18:: respectively which move the press head 13 down toward the stationary platen 11 and return it to position. Nuts 19 clamp the couplings '17 and 17a on the threaded lower ends of the rods 14 and nuts 20 fix the couplings 17 and 17a on the similarly reduced and threaded ends 18b of the piston rods 18 and 18a. "The double acting cylinders 21 and 21a which house the rams 18 and 18a are fixed to the underside of the press table or bed 11 in any suitable manner and flexible lines 22 and 23, and 22aand 23a, lead into opposite ends of the cylinders 21 and 21a respectively as usual.

" Presses of the typel have described thus far are conventional and form no part of the instant invention except as the various elements thereof cooperate with the novel leveling mechanism or system which will now be described. It.is to be understood that the press I have described is shown for the purpose of convenience of illustration .only and other presses or machines could have been illustrated.

V Secured .orrthe side wall ofthe table or bed 11 is, a guide plate or. frame. 24 which is provided with longitudinally disposed grooves 25 slidably accommodating an upper rack bar 26 and a lower rack bar 27 and maintaining them in substantial parallelism. End bars 25awhich are securedto the frame at 25b hold-the rack bars in the guide grooves 25. ,The rack bars 26 and 27 form part of a preloaded, mechanical system for measuring theamount that one ram is leading the other and transferring the information to a fluid metering assembly A which automatically corrects the condition. A yoke 28 having an elongated slot 29 and an. opening 29a to pivotally receive pins Sttwhich couple the rack bars to the yoke 28 is provided to connect the rack bars 'to a cylinder 31 which performs a preloading function for thejsystem. It will be seen that the system is connected piston 36 toward the racks 26 and 27 and accordingly tends to pull the racks to the right since it bears on the nut38 threaded in the right end of the cylinder.

A similar tapeor strap39 which is secured to the left end (Fig. l) of the upper rack bar 26 in any acceptable manner is trainedaround'a pulley 40'pivotally mounted as at 41 on the die bed 11 and is connected to'a transverselyextending lug 42 on the left hand coupling or link 17 as shown. Likewise a like metallic tape orstrap 43 which is secured to a transversely extending lug 44 on the righthand coupling 17 is connected to thelower rack bar 27. after passing around pulleys 45 and 46 which arepivotally mounted on the bed at 47 and 48. The tension cylinder 31 which, it will be observed, is pivotally connected to the yoke 28 at 49, thus serves to keep thestraps 32, 39, and 43 taut as the platen 13 descends and maintains. a constant and uniform tension on the system in all positions of the upper platen 13.- The system is arranged so that the cables 39 and 43 lead from the1sazme end of each rack bar and tend to pull the rack bars 26 and 27.'in the same direction when the platen 13 is descending. Plainly when the rams 18 and 18a are moving in synchronism .and'the ends of the platen 13 are in absolute parallelism the racks 26 and 27 will move longitudinally at the same rate. If one end of the platen 13. is moving at adifferent rate of speed than the other, however, .one rack bar will be moved at a more rapid rate than the other. 7

Mounted on the guide plate 24 by means of screws 50 or the like is. a bearing strap 51 (Fig. 4) which pivotally cups 56 fixed on the shaft 52 have socket portions 57 to receive the ball joints 54 and 55. The pinions 58 and 59 fit down over the socket portions 57 (Fig. 4) and have slots 60 (Fig. 6) accommodating the ends of the laterally projecting pins 61 on the ball joints 54 and 55. The slots 60 extend from the one side of each pinion substantially beyond pins 61 so that the pins 61 do not interfere with tilting of the pinions relative to the shaft 52 while, however, preventing rotation of the pinions without driving the shaft 52. The ball cups 56 have similar slots 62 permitting free tilting of the pins 61 with regard to the cups through a substantial are. i

The lower end of shaft 52 is rotatably accommodated within a bearing 63a secured on a crank lever 63 (see A. The shaft 52 can move axially-inbearing63a as Figs. 4 and 5) as at 63b and it will be seen that the opposite end of crank lever 63 is rigidly fixed to the operating shaft 64 of the annular fluid metering assembly should be apparent.

As shown in Figs. 2 and 3 the assembly A which is inverted in position for convenience of illustration comprises a housing 64a having a supply or inlet opening 1 65 and a pair of outlet openings 66 and 67 into which the pressure fluid proceeding into the housing through opening 65 is to be channeled in metered quantities dependent on the positions of the rams 18 and 13a. The various openings are threaded as at 68 so that the flexible hoses 69, 22, and 22a leading from the pump P (Fig. 8). l and to thecylinders 21 and 21a respectivelvmay be readilyconnected to the housing 64a. A sleeve 72 fixed in position in the valve housing 64a as shown has an opening 73 opposite the inlet 65 and a series of elongated slotted openings or ports 74 and 75 opposite the outlet openings 66 and 67 as shown.

Bolted to the housing 64a as at 76 is a head 77 which has a bearing 78 in an opening 79 for rotatably supporting the valve operating shaft 64. The inner end of shaft 1 64 has an annular sleeve 80 rotatable in the fixed sleeve 72 and it will be seen that the sleeve 80' has a series of slotted ports 81 and 82 generally opposite the openings 74 and 75 respectively. It will be observed that the slots 74 and 75 are-of slightly greater width than the slots j 81 and 82, however, all of the slots 74, 75, 81, and 82 tially.. When. the pointer is at zero position as in Fig. 4

the operating sleeve 80 is disposed as shown in Fig. 2 with the ports 74 and 75 slightly throttled. Accordingly, if the shaft 64 is turned in either direction the flow through one set of ports is increased while the flow through the other set is decreased. Because the flow to one cylinder can be increasedin this manner when the platen 13 gets out of line while the flow to the other cylinder is being decreased clearly the adjustment back to original position is considerably faster and a finer differential limit can be maintained.

In Fig. 8 I have illustrated a. hydraulic circuit ofv atype which may be employed to provide oil for the double acting cylinders in the usual manner.

tional designexcept for the metering assembly A through which oil passes to drive the pistons or rams 18 and118a* inthe one direction.

livery pump P has a line 87 leading to a hydraulic distributing valve V which in conventional systems channels oil to a particular end of each of the cylinders 21 and 21a-and returns .it from the opposite end of the cylinders dependent on which direction it is desired to moverams 18 and 18a. Inthe instant system a line 88 leads from- The system itself forms no part of the instant invention and is of conven' the lines 23 and 23a connecting to the cylinders 21 and 21a to return fluid from the lower ends of the cylinders when the rams are moving downwardly.

' The line 69 leads from the valve V to the inlet 65 of the fluid metering assembly as noted and pilot operated check valves 89 are interposed in the lines 22 and 22a which permit flow freely from the assembly A to the cylinders 21 and 21a and prevent flow from the cylinders to the assembly A when the pistons are moving in the opposite direction. Lines 90 lead from the check valves to the valve V and a line 91 returns fluid from the valve V to the reservoir R. Line 92 leads from the valve V to lines 23 and 23a to permit the pump to return the rams 18 and 18a upwardly. The valve V which is of common design and is available on the market is electrically operated by limit switches at the upper and lower limits of travel of the platen which reverse its position to reverse the direction of travel of the rams ornpistons 18 and 18a. V

In the operation of the press it will be assumed that the platen 13 is initially in raised or elevated position and it is desired to move it downwardly to engage the dies 12a and 12. Oil from the constant delivery pump P proceeds through linev 87 to the valve V and thence through line 69 to the metering assembly A where it is distributed to the lines 22 and 22a'and accordingly the cylinders 21 and 21a respectively. Oil from the lower ends of the cylinders at the same time returns through lines 23 and 23a to the valve V and thence through line 91 to the reservoir R. As the rams 18 and 18a move downwardly they pull the tapes 39 and 43 downwardly and the tapes pull the rack bars 26 and 27 to the left respectively. The tape 32 moves with the rack bars as the platen13 descends, of course, without in any way affecting the tension which is continuously placed on the rack bar system by the spring 37. As the rack bars are moved to the left they rotate the pinions 58 and 59 which, so long as the rack bars are traveling at the same rate of speed, do not affect the position of the crank arm 63 or the operating shaft 64. If the upper rack bar 26 begins to lag the lower rack bar 27 however, the rotating shaft 52 is pivoted in its bearing 51a and revolves the valve operating shaft 64 slightly in a clockwise direction as it is viewed in Fig. 2. This increases the flow through the sets of ports 82 and 75 while reducing it through the sets of ports 81 and 74 and the left end of the platen 13 quickly catches the right end of the platen. If the right end of the platen 13 begins to lag the left end of the platen clearly the rotating shaft 52 will be pivoted in the opposite direction and shaft 64 will be revolved slightly in the opposite direction. This, of course, reduces the flow through the sets of ports 82 and 75 and increases the flow through the sets of ports 81 and 74 until the right end of the platen catches up with the left end of the platen. Clearly the position of the rotating shaft 52 will .be changing all during the limited time the one end of the platen is catching up with the other and the mechanism does not hunt. The shaft 64 actually revolves a very limited distance less than the width of one of the ports 81 or 82 since the balancing mechanism immediately corrects the positions of the ends of the platen 13 before they can get very far out of line. At no time, in fact, can the platen ends be out of line more than a predetermined differential which is measurable in thousandths of an inch. With elongated ports of narrow'width provided as shown a very fine control can be exercised.

.In Fig. 1 the pistons 18 and 18a are shown as having descended all the way to the lower ends of cylinders 21 and 21a respectively. The platen 13 at this point trips a limit switch which reverses the slide valve V and causes fluid from pump P to proceed through lines 92, 23, and 23a to the lower ends of the cylinders. The pistons 18 and 18a are accordingly returned upwardly and the fluid in the upper ends of the cylinders exhausts through 6 lines and 91 to the reservoir R. In this position of the valve V the line 88 is closed to line 91.

In order to relieve pressure in the leading cylinder when the supply to that cylinder has been cut off a port 93 (Fig. 2) is provided in the housing 64a of the metering assembly A in communication with a port 94 in fixed sleeve 72 and a slot 95 in revolvable sleeve 80. When sleeve 80 has moved clockwisely (referring to Fig. 2) sufliciently so that the fluid from ports 81 is blocked by sleeve 72 slot 95 communicates with the right end port 74 and fluid bleeds through line 96 to the reservoir R. Similarly when the other cylinder leads and sleeve 80 has revolved counterclockwisely sufliciently so that the fluid from ports 82 is blocked by sleeve 72 slot 95 communicates with the left end port 75 and fluid bleeds out line 96 to speed up the leveling action.

The non-elongatable, flexible tape and. rack bar system which incorporates the tensioning cylinder 31 is a safety feature of considerable importance, of course. Except when the mechanism is not operating properly the tension imposed by the spring cylinder 31 will be uniform for all positions of the platen 13. In practice the scale 36 will be used to set the differential within which the leveling mechanism will operate and can also be used to set the position of a pair of safety limit switches (not shown) which could be disposed on opposite sides of crank arm 63 so that in the event of a leak in the fluid system or the like they would shut down the press. The fact that arm 63 swings in an arc makes it ideal for operation with safety switches of this type.

Because the particular mechanism disclosed is connected to the rams and permits the rack bars to be ar ranged in horizontal disposition on the bed 11 rather than in vertical position the press is not limited to factory spaces having considerable head room by the rack bars. The rack bars 26 and 27 can move longitudinally within the length of the press and obviously do not in any position extend above the press. The tapes 32, 39, and 43 permit the mechanism to be used with presses having platens of considerable length and are unique because they are not elongatable as cables, for instance, are.

It should be obvious that I have perfected automatic balancing or leveling mechanism of improved design which is greatly superior in a great many respects to prior art systems.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention rather than as limiting the same in any way since it is contemplated that various changes may be made in the various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

In the claims:

1. In a press or the like having mechanism including two sections movable in a predetermined path and at least two fiuid pressure cylinders having rams therein for moving said sections simultaneously, a common fluid pressure system for said cylinders including a conduit leading to each cylinder, fluid meteringmeans in the system operative to channel pressure fluid in variable quantities to said conduits, a rotatable operating shaft in said metering means rotatable about its longitudinal axis a metering element on said shaft operative to finely adjust the flow of fluid out of said metering means to each ram, a mechanical system connected to each ram and the mechanism including a pair of elements each traveling at a rate in accordance with the rate of travel ofeach ram, and means connected to" said operating shaft of the metering means and actuated by said pair of elements rotating said shaft about its axis in either direction dependent on which ram leads the other and the scope of the lead.

2. The combination defined in claim 1 in which said mechanical system includes said pair of elements arranged in parallelism substantiallyperpendicular to the path of travel of said sections, a flexible, non-elongatable line connecting 'one end ofone element independently to one of the'rams, guidemeans, and a similar flexible line leading from the like end of said other element in the same direction and passing-around said guide means connected to the other ram so that said elements both travelin a common direction away from one of said sections and toward another section when the rams are actuated, a yoke pivotally connecting the opposite ends of the elements and a single flexible line connecting the yoke to said mechanism. a I a 3, The combination defined in claim 1 in which said elements comprise a pair of rack bars arranged in parallelism substantially perpendicular to the path of travel of said-sections, and said system includes flexible line means connecting like ends of said rack bars to the rams and to the mechanism in a manner so that said rack bars both travel insubstantial parallelism in a common direction away from'one of said sections and toward another section when the rams are actuated.

4; The combination defined in claim 1 in which said elements comprise rack bars, a rotary shaft pivotally supported intermediate the rack bars and connected at one end to the operating shaft, and spaced apart pinions keyed on said'shaft and in mesh with'the said rack bars respectivelypivoting the last defined shaft when one rack bar'leads the other.

5. In a press having an elongated, movable platen and a stationary platen, a fluid pressure cylinder near each end of the platen having a ram therein for actuating the movable platen toward the stationary'platen, a fluid pressure system including a source of fluid pressure supply and conduit'means leading to the ends ofthe cylin: ders remote from the stationary platen, fluid metering means in the system operative to channel pressure fluid in variable quantities to saidconduits, an operatingshaft in said fluidcmetering means operative to adjust the flow of fluid out of said fluid-metering means to each cylinder, a pair of rack bars on said press arranged in parallelism substantially perpendicular to the path'of travel of said movable platen, flexible line means connecting said rack bars'to the rains and to the movableplaten in a mannersonthat said rack bars travel in substantial p'arallelism'in a common direction when the rams are actuated, a pretensioning cylinder for placing a constant load on said flexible line means connected therein, arrota'ry shaft pivotally supported on the press intermediate the rack bars and connected to the operating shaft to function as a crank arm therefore, pinions swivelly mounted on said rotary shaft but keyed thereto to drive the shaft in mesh with the rack bars whereby said pinions cause pivoting of said shaft when one rack bar leads the other and accordingly actuate the operatingshaftito adjust the flow of pressure fluid to said rams and correct the mahalignment.

6 In a press having an elongated, movable platen and the c'onduitsleading to the cylinders, said housing having a set of radiallyspaced, axially elongated slots opposite each outlet, a sleeve in said housing, and into which said inlet leads, having axially elongated slots radially spaced to cooperate with said previously mentioned slots and vary the flow through the sets of slots in accordance with the rotary position of the sleeve, said slots in the sleeve being arranged with respect to the slots in thehousing .so that revolution of the sleeve in a particular direction increases flow through the sets of slots to'one outlet and decreases flow through the set to the-ot her sets of slots to-the other outlet, a shaftifixed to said sleeve, a pair of'rack bars supportedin parallelism substantially perpendicular to the path of travel of said movable platen, a flexible'metallic tape connecting one end of one of the rack bars to one of the rams, guide 7 pulleys on the press, and a similar tape leading from the adjacent end of the other rack bar in the same'direction as said other tape and passingaround said guide pulleys connected to the other ram so that said tapes travel in a common direction when the rams are forcing the mov able platen toward the fixed platen, a yoke pivotally connecting the opposite ends of the rack bars and permitting one to travel longitudinally a limited distance with respect to the other, a similar metallic tapeconnected to said movable platen, and a tensioning cylinder connecting said yoke and'said latter tape to impose apredetermined load on the rack bar system, a bearing on said press intermediate said rack bars, a rotary shaft having an intermediate ball joint swivelly supported by said heating,

ball joints on said rotary shaft adjacent each rack, pinions Lmountedcon said latter ball joints, and keyed thereto to,

drive said shaft, mesh with said racks, and a crank arm connecting one end of said sleeve shaft with the last defined shaft so that tilting ofsaid latter shaft, when one rack bar leads the other responsive to uneven travel of said rams, tilts saidrotary shaft and revolves said sleeve to adjust the flow oftflu id through to said outlets andcorrect the positions of said rams. p

7. The combination defined in claim 6 in-which means in said housing-bleeds fluid from a cylinder which leads when the supply of fluid to that cylinder has been substantially cut off; 7 I 7 V 8. ma press or the like having mechanism including a frame, at least two sections-movable simultaneously in a predetermined path, a fluid pressure cylinder having a ram therein for each section moving said sections simultaneously, each ram and the section it moves comprising movable means;fluid pressure system for said cylinders including a conduit leading to each cylinder;'fluid metering means in the system operative to cause the flow of pressure fluid in varied quantities to said conduits; an operating member incorporated with said meteringmeans operative to finely adjustthe flow of fluid .to each ram; dilferential'measuring means including a pair of elements connected to said operating member for moving the same in accordance with whether one ram leads the other; and a part connected to one section and a part connected to the other section exerting pulls on said pair of elements moving these elements in the same direction ,toward one of said sections and away from another section, astthe rams move said sections simultaneously.

9. The combination defined in'claim 8 in which said parts include individual lines connected at one end to said movable means and extending adjacently in generally parallel relationincthe same directiontfrom the differential measuring means. 5 7 q I f a 10. The ccmbination defined inclaim 8 in which said pair 'of elements comprise spaced apartracks. towhich said parts' are connected; said dilTerentia-l measuring means includes also a rotary'shaft supported intermediate the racks'for rotation about its axis and forlpivotal inovement in -its 'plane connected to said operating member; and pinions onthe ends of said shaft in mesh with each rack to pivotfthe shaft ,when one rack leads. the other.

11. The combination defined in claim 8 in which said press includes a bed toward which'said sectionsmove; said differential ,measuring meansis mountedQon said bed between said sections;v guide means also on said bed adjacent said latter means; and said parts incIHde indi vidual lines, one of which is reeved around said guide means to exert a pull in the same direction as the-other,

line e 9 at least two sections movable in a predetermined path and at least two fluid pressure cylinders having rams therein for moving said sections simultaneously; fluid pressure system including a source of fluid under pressure and conduits leading to each cylinder; a fluid metering means connected in the system between the source and the said conduits; sleeve means included as part of said means and having a plurality of spaced apart sets of ports in the periphery thereof; an inlet to the interior of said sleeve means for passing the pressure fluid thereto from said source; housing means in which said sleeve means is mounted for relative rotation having sets of spaced apart ports therein each adjacent said sets of ports in said sleeve means so that the sets of ports in said sleeve means and housing means communicate; outlets in said housing means communicating with different sets of ports in said housing means and connected separately to said conduits leading to the cylinders; the different sets of ports being so spaced in the sleeve means and housing means that relative rotation of said sleeve means and housing means in one direction increases the flow to one outlet while decreasing flow to the other outlet, and the reverse is true when rotation is in the opposite direction; revolvable shaft means connected to one of said housing and sleeve means for rotating one relative to the other and increasing the flow through adjacent sets of ports in the housing means and sleeve means to one outlet while decreasing the flow through adjacent sets of ports in the housing means and sleeve means to the other outlet; and means responsive to uneven travel of the rams for operating said shaft means to cause one ram to catch the other.

13. In a press or the like having mechanism including a frame; at least two sections movable simultaneously in a predetermined path; a fluid pressure cylinder having a ram therein for each section moving said sections simultaneously, each ram and the section it moves comprising movable means; fluid pressure system for said cylinders including a conduit leading to each cylinder; fluid metering means in the system operative to cause the flow of pressure fluid in varied quantities to said conduits; an operating member incorporated with said metering means operative to finely adjust the flow of fluid to each ram; individual flexible lines connected fast to both said moveable means and to said ditferential measuring means transmitting the relative positions of said rams to said differential measuring means as the rams move said sections simultaneously to permit the differential measuring means to measure the lag or lead of one of the rams relative to the other.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,258 Cannon Aug. 31, 1943 2,350,795 Monier June 6, 1944 2,484,908 Purcell Oct. 18, 1949 FOREIGN PATENTS 484,313 Germany Oct. 15, 1929 

